Refrigerator for testing instruments under conditions of cold and low pressure



E. D. v. PLATON 2,502,480 REFRIGERATOR FOR TESTING INS'I'RUIENTS UNDER connrnous OF cow m: LOW passsuns Filed July 2, 1943 2 Sheets-Sheet 1 April 4, 1950 INVENTOR. EDA'IQND a K PMTUIV April 4, 1950 a D. v. PLATON REFRIGERATOR FOR TESTING INSTRUMENTS UNDER CONDITIONS OF GOLD AND LOW PRESSURE 2 Sheets-Sheet 2 Filed Juiy 2, 1943 &

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Patented Apr. 4, 1950 REFRIGERATOR FOR TESTING INSTRU- MENTS UNDER CONDITIONS OF "GOLD AND LOW PRESSURE Edmond D. Platon, Lyon, France, assilnor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application July 2, 1943, Serial No. 493,281

In France May 11, 1940 Section 1, Public Law 690, August 8, 1946 Patent expires May 11, 1960 1 Claims. 1

- The present invention relates to apparatus for the production of intense degrees of cold and more particularly to refrigerating apparatus for the testing of measuring devices under definite conditions of temperature and pressure.

It is known that certain instruments, e. g. altimeters used in aviation, have to operate satisfactorily at a very low pressure and at temperatures that may reach -50 C. In particular, the invention aims at providing a refrigerating apparatus that can duplicate these conditions while still occupying limited space and being capable of rapid operation.

The invention is explained hereunder with reference to one example of an embodiment and the respective appended drawings, in which:

Fig. 1 is a vertical sectional view of a refrigerating apparatus that incorporates some features of the invention;

Fig. 2 is a horizontal sectional view of the same apparatus on the line AA of Fig. 1.

The described example of embodiment comprises a refrigeration system of the cascade type including a high temperature stage and a low temperature stage, each of which stages is constituted by a fluid circulating circuit separate and distinctfrom the other except that the two circuits are in direct heat exchange relationship along certain coiled portions thereof.

The first refrigerator, which is the only one illustrated, permits of very rapid cooling of the refrigerant liquid circulating in the low temperature stage.

Fig. 1 shows at I the evaporator in which the instruments to be tested are placed. It consists of two cylinders 2 and 3 with a space for the refrigerant liquid between them. The two cylinders are excentric in relation to each other in such a way that variations of volume of the liquid do not result in too important variations of level, as this would afiect the heat exchange surfaces too much.

Within cylinder 3 there are racks 4 and ill of good conducting metal, e. g. copper; racks 4 are provided with apertures 5 in which instruments to be tested, e. g. altimeters, are placed. These racks serve for extracting the heat from the altimeters and the surrounding air by radiation and/or conduction, since convection can not effectively take place in the vacuum in which this evaporator compartment has to be carried. The evaporator shown in the drawing can contain 8 altimeters, 4 on the front side and 4 onthe rear side.

The evaporator works by means of the refrigerant liquid being between walls 2 and 3 up to the height of the top of the first cylinder. A dome 6 provided on the upper part 01' the outer cylinder communicates with the compartment of the evaporator by means of an opening shown at 1 (Fig. 1), thus avoiding liquid hammering toward the compressor.

In Fig. 2 two transparent plates II and I2 provided with rubber washers l3 and H permit 'of overall sealing of the evaporator for the purpose of maintaining a vacuum within it.

Furthermore, in order to avoid condensation efiects, additional closing members are provided and these consist of the two pairs of glass panels l9 and 20, one pair on each side. These panels are mounted on hinged frames 2| and 22 with rubber packings 24.

The evaporator assembly which rests on supports is installed in an insulating casing 9 which also houses the circuits and certain associated elements (not including compressors, driving motors and the like).

Two doors l5 and i6 permit easy access to the inside of the apparatus and these doors are themselves provided with transparent port closures l1 and 18, of dimensions corresponding to panes l I and I2, for observation of the instruments being tested.

A liquid separator 63 is provided intermediate the evaporator and the compressor. 21 indicates a thermostatic expansion valve for the feeding of refrigerant fluid to the low temperature evaporator. 48 designates a heat exchange coil for reaction with the flow circuit of a high temperature stage (not shown) and leading to the compressor on the one side and to the evaporator through conduit 49 on the other side. The vapors from the evaporator 2 and 3 are returned through the pipe 50 from the dome 6 through the separator tank 63 to the compressor.

Suitable low pressures are maintained for testing purposes in the test chamber by a. suction device connected to inner cylinder 3 through a pipe line 58.

The assembly of the devices described in the invention is to be used with a refrigeration plant of small and even of transportable size which can very rapidly produce in practical use extremely low temperatures of the order of -50 C. In one example of an embodiment made a temperature of 50 C. was obtained alitera period of operation of not more than one hour, and it is possible to attain a temperature of 62 C.

What is claimed is: V

1. A storage compartment for a refrigerating system comprising a member with sealing means at each of two opposite sides, racks mounted in said member and formed of a material adapted to absorb heat under sub-atmospheric pressure conditions, said racks having apertures to receive objects, means about said member for the circulation of a refrigerant thereabouts, and means whereby a sub-atmospheric pressure may be developed within said member and about instruments carried by said ribs.

2. In a refrigerating system for testing instruments at low temperature and pressure, a storage compartment comprising a cylinder with closing means at each of two opposite sides and metal racks mounted within said cylinder adapted to absorb heat under sub-atmospheric pressure conditions and provided with channels to receive instruments, means about said cylinder for the circulation of a refrigerant thereabouts. and means whereby a sub-atmospheric pressure may be developed within said cylinder and about such instruments.

3. In a refrigerating system the combination of a storage compartment adapted to operate under low temperature and pressure comprising a member having a heat exchanging wall provided on the inside with racks having openings to receive objects and an evaporator comprising a jacket enveloping the heat exchanging wall of said member and spaced therefrom to provide a space between said wall and jacket for refrigerating fluid, means whereby a refrigerant is circulated in the space between said member and said jacket and means whereby a sub-atmospheric pressure may be developed within said member and about objects in the openings in said ribs.

4. In a refrigerating system the combination of a cylindrical storage compartment having a heat exchanging wall adapted to operate under low pressure conditions provided on the inside with apertured ribs to receive objects and at each of its two ends with sealing means and a second cylinder fitted over the heat exchanging wall of said first cylinder to provide an enclosure for refrigerating fluid between said cylinders, said second cylinder having an opening for fluid, perforations to release vapor, a dome adapted to receive vapor located on the outside of said Number 4 second cylinder over said perforations and exit means for vapor associated with said dome.

5. In a two-temperature stage refrigerating system (for subjecting articles to extreme conditions of cold and vacuum, the combination of a storage compartment comprising a cylinder having a heat exchanging wall containing apertured racks and provided at each of two ends with sealing means and means comprising a second cylinder fitted over the heat exchanging wall of said first cylinder to enclose a space for compressed refrigerating fiuid between the walls of said cylinders, said second cylinder having an opening to admit fluid, perforations to release vapor, a dome placed outside said second cylinder over said perforations to receive vapor and exit means for vapor associated with said dome.

6. In a two-stage refrigerating system according to claim 5, the combination in which said first cylinder is eccentric with respect to said second cylinders.

"I. In a system for applying low temperature to instruments to be tested, the combination of a compartment to receive said instruments, a multiple circuit refrigerating means for maintaining the desired low temperature in and around said compartment, said compartment including a plurality of racks extending longitudinally of the compartment to hold the instruments to be tested, and a pair of cylindrical elements enclosing all of said racks, the outer one of said cylindrical elements being eccentrically arranged in relation to the inner element to pro vide a fluid receiving space of variable crosssectionv between said two cylindrical elements.

EDMOND D. V. PLATON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date 1,253,895 Shipley Jan. 15, 1918 1,942,458 Taylor Jan. 9, 193a 2,026,079 White Dec. 31, 1935 2,109,002 Warren Feb. 22, 1938 2,218,632 Baird Oct. 22, 1940 

